Since WWII the M14 Aiming Post Light has been used for artillery and mortar operations to maintain orientation despite possible movement of the gun when fired. Each light consisted of two size D flashlight batteries in a brass case having an on-off switch, an incandescent bulb and a reflector/lens filter. To avoid confusion, half the lights have a red filter and half have a green filter. Each howitzer or mortar uses one of each. They presently cost over $25 each.
Aiming post lights are placed forward of their guns a distance from 50 to 100 meters. They drain the batteries in a night or so and require replacement, sometimes a hazardous task, particularly when the enemy is close by. Obviously an aiming light that will survive an engagement without replacing batteries is preferred.
The aiming post light in the Hubbard et al application consisted of a flashlight with a LED and integrated circuitry that had to be attached to the flashlight contacts with clips, which was unacceptable from a ruggedness viewpoint, or soldered to the contacts, which made it nonreversible back to flashlight use again. FIG. 3 of Hubbard et al. overcomes this with a bulb having a capacitor 52 as the base and an integrated circuit 56 on the bottom. This posed fabrication problems.